WO2012117209A1

WO2012117209A1 - Component made of composite material comprising boss elements and corresponding production method

Info

Publication number: WO2012117209A1
Application number: PCT/FR2012/050436
Authority: WO
Inventors: Loïc OLIVIER
Original assignee: Snecma
Priority date: 2011-03-03
Filing date: 2012-03-01
Publication date: 2012-09-07
Also published as: EP2681036A1; US20140017074A1; BR112013020890B1; FR2972129A1; RU2591148C2; CN103415388A; FR2972129B1; RU2013144380A; US9550340B2; CN103415388B; CA2827806A1; EP2681036B1; BR112013020890A2; CA2827806C

Abstract

A fibrous structure (100) for reinforcing a component made of composite material is obtained by the multi-layer weaving of a plurality of layers of warp threads (101) and a plurality of layers of weft threads (102). The fibrous structure (100) also comprises fixing elements (120, 130) at least on one of its faces, each fixing element comprising a body (121, 131) arranged under threads (101₁, 102₂) on a face of the fibrous structure, and fixing portions (122, 123; 132, 133) situated above said threads.

Description

i

PIECE OF COMPOSITE MATERIAL COMPRISING ELEMENTS

BOSSAGE

Background of the invention

The present invention relates to the production of composite material parts and more particularly of parts equipped with fastening or fastening means in particular for the support of equipment.

A field of application of the invention is more particularly the production of parts of structural composite material, that is to say pieces of structure with fiber reinforcement densified by a matrix. The composite materials make it possible to produce parts having a lower overall mass than these same parts when they are made of metallic material. The fibrous reinforcement of the composite material parts of standard geometry, such as ferrules or panels, is generally made in one piece by multilayer weaving between layers of warp son and layers of weft son. Once the reinforcement densified by a matrix, it ensures a good distribution of local mechanical forces on the entire room thus giving the latter a good structural character and high mechanical strength.

In the case of parts made of metallic material, equipment or supports intended for fixing such equipment are directly attached to the part, in particular by welding or by means of holes in the part allowing the passage of fastening members such as screws. or rivets.

However, in the case of a composite material part, it is not possible to weld supports or equipment directly on the part. Moreover, the production of holes mechanically weakens the part because they create interruptions in the continuity of the transmission paths of the mechanical forces. In the case of parts intended for the aeronautical industry, such as turboprop casings, the bores are prohibited in the retention zone of the part.

Object and summary of the invention

It is therefore desirable to have composite material parts for attaching equipment to the latter, in particular by welding or brazing, and without requiring holes in the structural body of the part.

For this purpose, according to the invention, it is proposed a fiber reinforcement structure of composite material part, said structure being obtained by multilayer weaving between a plurality of layers of warp son and a plurality of layers of weft son, characterized in that the fibrous structure further comprises at least one of its faces one or more fastening elements, each fastening element comprising a body arranged at least partly under wires present on one face of said fibrous structure and at least one fixing portion located above said wires.

Thus, it is possible to form, from the fibrous structure according to the invention, composite material parts comprising fasteners secured to the part and whose fixing portions may be used for attaching equipment without weakening the character. structural of the room.

According to a first aspect of the invention, each fastening element is made of metal material, which allows the attachment of equipment or other parts of fasteners on the part including welding, brazing or metal bonding.

According to a second aspect of the invention, each fastening element comprises first and second fastening portions extending on each side of said body and above the threads of the fibrous structure.

According to a third aspect of the invention, the first and second portions have a flattened shape.

According to a fourth aspect of the invention each fixing portion corresponds to a fixing lug.

According to a fifth aspect of the invention, each attachment portion is extended by a retaining tab disposed under one or more threads of the fibrous structure.

The subject of the invention is also a part made of composite material comprising a fibrous structure according to the invention.

According to one embodiment of the invention, each fixing element further comprises a jumper fixed on each fixing portion. According to one aspect of the invention, the part constitutes an aeronautical engine casing.

The invention also relates to a turboprop comprising an aeronautical engine casing according to the invention.

The invention also relates to an aircraft equipped with at least one turboprop engine according to the invention.

The present invention further provides a method of making a composite material part comprising the following steps:

- producing a fibrous structure by multilayer weaving between a plurality of warp layers and a plurality of weft layers,

- shaping of the fibrous structure,

densification of the preform by a matrix,

characterized in that it further comprises, prior to densification of the preform, insertion under son present on one face of the fibrous structure of a body of one or more fastening elements, each fastening element comprising in addition to at least one fixing portion situated above said wires.

According to a first aspect of the method of the invention, during the insertion under son accessible from a face of the fibrous structure of the body of each fastening element, said son are relaxed so as to allow the passage of each fastener element said wires being then retensioned.

According to a second aspect of the invention, each fastener is disposed on the fibrous structure being woven, with one or more additional layers being woven over each fastener.

According to a third aspect of the method of the invention, during the insertion of each fastener under threads of the fibrous structure, the fastener element is in the form of a rod. After said insertion, at least a portion of the fastener element located above the threads of the fibrous structure is crushed to form a fastening portion.

According to a fourth aspect of the process of the invention, during the densification of the preform, the face opposite to the fibrous structure each attachment portion of a fastener is processed so as to be devoid of matrix upon completion of the densification.

According to a fifth aspect of the method of the invention, each fixing portion is extended by a retaining tab which is arranged under one or more threads of the fibrous structure during insertion of the fastening element (s) under threads of the structure .

According to a sixth aspect of the method of the invention, each fixing element further comprises a jumper fixed on each fixing portion.

Brief description of the drawings

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the appended drawings, in which:

FIG. 1 is a perspective view of an aircraft engine casing according to one embodiment of the invention,

FIG. 2 is a diagrammatic perspective view of part of a fibrous structure for the manufacture of the aircraft engine casing of FIG. 1,

FIGS. 3A to 3D are enlarged scale sectional views showing an example of the arrangement of weft yarns in the fibrous structure of FIG. 2,

FIG. 4 is a schematic perspective view showing the insertion of two fixing bases into the fibrous structure of FIG. 2;

FIG. 5 is a schematic perspective view showing the fibrous structure of FIG. 2 after insertion of the fixing bases,

FIG. 6 is a schematic perspective view showing the shaping of the fibrous structure of FIG. 5 prior to densification, FIG. 7 is a schematic perspective view showing the part obtained after densification of the fiber preform of FIG. 6, FIG. 8 is a diagrammatic perspective view showing the portion of the aircraft engine casing of FIG. 1 provided with fixing bases, FIG. 9 is a diagrammatic perspective view showing the part of the aeronautical engine casing of FIG. 1 provided with mounting bases and on which riders are fixed,

FIG. 10 is a schematic perspective view showing the insertion of two rods for forming fastening elements in a fibrous structure according to another embodiment,

FIG. 11 is a schematic perspective view showing the fibrous structure of FIG. 10 after insertion of the stems and crushing of the ends of one of the stems,

FIG. 12 is a schematic perspective view showing the fibrous structure of FIG. 10 after densification,

FIG. 13 is a schematic perspective view showing the insertion into a fibrous structure of a fastening base according to another embodiment,

Figure 14 is a schematic perspective view showing the fibrous structure of Figure 13 after densification.

Detailed description of embodiments

The invention is generally applicable to the production of composite material parts comprising a fiber reinforcement densified by a matrix and whose body is intended to maintain or support equipment (housings, cables, etc.). By "body" is meant here any structural part of a part, in particular but not exclusively, of a form of revolution such as a shell.

According to the invention, one or more fastening elements are integrated on at least one surface of the body to allow in particular the retention or attachment of equipment without requiring drilling in the body of the part.

FIG. 1 illustrates a casing 10 of an aircraft engine made of composite material formed of a shell 11 comprising first and second fastening elements 12 and 13 intended to allow the attachment of equipment on the shell 11 or the passage and maintaining cables (not shown in Figure 1).

FIG. 2 very diagrammatically shows a fibrous blank 100 intended to form the fibrous reinforcement of the shell 11 of the casing 10. The fibrous blank 100 is obtained, as shown diagrammatically in FIG. 2, by multilayer weaving made in a known manner by means of a jacquard loom on which a bundle of warp yarns 101 or strands in one is arranged. plurality of layers, the warp son being bonded by weft threads 102,

In the example shown, the multilayer weave is an "interlock" weave. "Interlock" weaving is here understood to mean a weave in which each layer of weft threads binds several layers of warp yarns with all the threads of the same weft column having the same movement in the plane of the weave. .

By "son" is meant here strands each formed of a set of non-braided filaments. In particular, each son may correspond to a strand of 3000 to 12000 filaments.

Other known types of multilayer weaving may of course be used.

The fibrous blank according to the invention may be woven, in particular, but not exclusively, from yarns of carbon fibers or of ceramics such as silicon carbide.

As illustrated in FIG. 2, the fibrous blank 100 has a shape of strip extending in length in a direction X, the blank 100 being intended to form, after shaping and densification, the shell 11 of the casing 10.

An interlock woven multilayer weave mode of the blank 100 is schematically shown in FIGS. 3A-3D which are respectively enlarged partial views of successive cutaway planes. In this example, the blank 100 comprises 6 layers of warp son 101 extending in the X direction. In FIGS. 3A to 3D, the 6 layers of chain strings C ₁ to C ₆ are linked by weft threads T _{ at T ₅ . For the sake of simplification, only 6 layers of warp yarns and 5 layers of weft yarns are shown here, of course depending on the dimensions (width and thickness) of the fibrous structure that is to be obtained, the latter may be made with a number of layers of warp and weft son and a number of threads per layer much larger. At the end of the weaving, the nonwoven warp and weft yarns are cut to extract the blank 100 shown in FIG. 2 as it comes from the multilayer weave.

Once the fibrous blank 100 has been formed, fastening bases 120 and 130 are inserted under threads of the fibrous structure 120 as illustrated in FIG. 4. In the example described here, the element 120 and 130 respectively is formed. a body 121, 131 respectively, at the ends of which extend two fastening portions 122 and 123, respectively 132 and 133, which have a flattened shape. The fixing bases 120 and 130 are preferably, but not exclusively, made of metallic material in order to allow the fixing by welding or soldering of other parts of fasteners or equipment on the fixing portions 122, 123, 132 and 133.

Still in the embodiment described here, warp son 101i and 101 ₂ are pulled locally (Figure 2) to relax them and allow the passage of the bodies 121 and 131 respectively of the bases 120 and 130 under these son.

Once the bases 120 and 130 thus positioned, the warp son 101i and 101 ₂ are retolded to be plated on the bodies 121 and 131 as shown in Figure 5.

The fiber blank 100 is then shaped to form the shell 11 of the casing 10 of FIG. 6. For this purpose, as illustrated in FIG. 6, the fiber blank 100 is shaped on a mold 140, here having the shape of a mandrel and corresponding to the internal shape of the housing 10 to achieve. The two free ends of the blank 100 may be, for example, stitched together before densification or simply superimposed, the latter being bonded together during densification. This gives a fiber preform 160 ready to be densified. In alternative embodiments, the fibrous blank has a length corresponding to several times the circumference of the casing.

The fiber preform 160 is then densified, which consists in filling the porosity of the preform, in all or part of the volume thereof, with the material constituting the matrix. The matrix of the composite material constituting the aerodynamic profile structure can be obtained in a manner known per se according to the liquid method.

The liquid process consists in impregnating the preform with a liquid composition containing an organic precursor of the matrix material. The organic precursor is usually in the form of a polymer, such as a resin, optionally diluted in a solvent. The preform is placed in a mold which can be sealed with a housing having the shape of the molded end piece. Here, the preform is placed between the mold 140 and a counter-mold 150 in two parts 151 and 152 respectively having the outer shape and the inner shape of the housing to be produced. Once the counter mold 150 is closed, the liquid matrix precursor (for example a resin) is injected throughout the housing to impregnate the entire fibrous portion of the preform.

The transformation of the precursor into an organic matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after removal of the optional solvent and crosslinking of the polymer, the preform being always maintained in the mold having a shape corresponding to that of the piece to realize. The organic matrix may in particular be obtained from epoxy resins, such as, for example, the high performance epoxy resin, or liquid precursors of carbon or ceramic matrices.

In the case of the formation of a carbon or ceramic matrix, the heat treatment consists in pyrolyzing the organic precursor to transform the organic matrix into a carbon or ceramic matrix according to the precursor used and the pyrolysis conditions. By way of example, liquid carbon precursors may be relatively high coke level resins, such as phenolic resins, whereas liquid precursors of ceramics, in particular of SiC, may be polycarbosilane type resins (PCS). or polytitanocarbosilane (PTCS) or polysilazane (PSZ). Several consecutive cycles, from impregnation to heat treatment, can be performed to achieve the desired degree of densification.

According to one aspect of the invention, the densification of the fibrous preform can be carried out by the well-known molding process. transfer called RTM ("Resin Transfer Molding"). According to the RTM method, the fiber preform 160 is placed between a mold and a counter-mold respectively presenting the outer shape and the inner shape (such as the mold 140 and against-mold 150) of the casing to be produced. A thermosetting resin is injected into the internal space delimited between the piece of rigid material and the mold and which comprises the fibrous preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the evacuation ports of the latter in order to control and optimize the impregnation of the preform with the resin.

The resin used may be, for example, an epoxy resin. Suitable resins for RTM methods are well known. They preferably have a low viscosity to facilitate their injection into the fibers. The choice of the temperature class and / or the chemical nature of the resin is determined according to the thermomechanical stresses to which the piece must be subjected. Once the resin is injected into the entire reinforcement, it is polymerized by heat treatment in accordance with the RTM method.

Whichever densification method is used, care should be taken to avoid resin deposition or matrix formation on the opposite side of the fibrous blank of the attachment portions 122, 123, 132 and 133, for example by scraping the resin flash present on this face or by any other treatment for cleaning it.

After injection and polymerization, the part is demolded. Finally, the piece is cut away to remove the excess resin and the chamfers are machined to obtain a part the housing 10 of Figure 7 formed of the shell 11 which has on its outer surface the attachment portions 122, 123, 132 and 133 fastening bases 120 and 130. As shown in Figure 8, the bodies 121 and 131 respectively of the bases 120 and 130 are retained on the ring 11 of the housing both by the warp son 101i and 101 ₂ and by the polymerized resin 103 (matrix). In this case, the fastening elements of the composite material part according to the invention consist of fastening bases 120 and 130.

As shown in FIG. 9, the portions 122, 123, 132, and 133 can be used to attach jumpers 125 and 135. Specifically, the jumper 125 includes an arch-shaped body 128 which has at its ends flattened portions 126 and 127 which are respectively fixed to the attachment portions 122 and 123 of the base 120, for example by welding, brazing or metal bonding. Similarly, the jumper 135 comprises a body 138 in the form of an arch which comprises at its ends flattened portions 136 and 137 which are respectively fixed to the fixing portions 132 and 133 of the base 130, for example by welding brazing or metal bonding. In this case, the fastening elements 12 and 13 of the casing 10 consist respectively of the fixing bases 120 and 130 and the jumpers 125 and 135.

According to an alternative embodiment, one or more devices are fixed directly to the fixing portions 122, 123, 132 and 133 of the fixing bases 120 and 130 for example by welding, brazing or metal bonding. In this case, the fixing elements of the housing consist solely of the bases 120 and 130.

On the other hand, in some cases, such as when the fiber blank is prestressed, the warp or weft threads of the blank may be difficult to relax. In such cases, the insertion of fasteners having relatively bulky parts such as flattened fastening portions may be difficult. For this purpose, the present invention proposes to use fastening elements initially having a stem shape, cylindrical, rectangular or other, which can be more easily inserted under one or more son, then to shape the fixing portions after insertion.

By way of example, FIG. 10 illustrates a fibrous blank 200 obtained by multilayer weaving, for example by interlock weaving, between a plurality of layers of warp yarns 201 and a plurality of layers of weft yarns 202, these being woven together with prestressing. Elements in the form of cylindrical rods 22 and 23, for example made of metallic material, are inserted under the warp son 201i and 201 ₂ . Thanks to their compact form, the elements 22 and 23 can be slid under string 20 li and 2012 without having to relax them. Once the elements 22 and 23 thus inserted, their ends are crushed, for example by means of a clamp 240, to form fixing portions as shown in Figure 11. After crushing the ends of the elements 22 and 23 and after forming and densification of the blank 200 as shown in Figure 12, there is obtained a composite material part 250 comprising two fastening elements 220 and 230 comprising bodies 221 and 231 retained on the piece 250 at the same time by the warp yarns 201 _L and 201 ₂ and by the polymerized resin 203 (matrix) and at the end of which are present fastening portions 222, 223, 232 and 233 having a flattened shape making it possible to preserve sufficient area for attachment of other elements such as jumpers or equipment attachment brackets.

Many alternative embodiments of the invention can be envisaged. Such variants concern in particular:

- the number and type of yarns (warp or weft) under which the fasteners can be inserted,

the shape of the fastening elements both as regards the shape and the dimensions of the body as the fixing portions of these elements,

the material of the fastening elements which is not limited to a metallic material,

the number and the arrangement of the fastening elements on the surface of the part, several of which can be used together or joined together to form a fastening base, particularly in the case of fastening heavy equipment,

- Fixing means used to attach equipment to the fasteners such as welding, brazing, screwing, clamping, etc.

In addition, the shape and dimensions of the composite material parts made with the fibrous structure of the invention can be varied and not be limited in particular to parts having a ferrule-shaped structural body but to any other type of shape ( for example ferrule sectors or flat or curved panels) on which one or more fasteners can be integrated according to the invention.

According to an alternative embodiment, the fastening base may comprise a retaining tab extending at the ends of each fastening portion in order to increase the mechanical strength of the base, particularly with respect to the tearing forces which can be exercised on this last. As illustrated in FIG. 13, a fixing base 320 comprises a body 323 which comprises at its ends a first and second fixing portions 322 and 324. The first fixing portion 322 is extended on the opposite side to the body 323 by a first leg retainer 321 while the second portion is extended on the opposite side to the body 323 by a second retaining tab 325. The base 320 is inserted into a fibrous blank 300 formed in the same manner as previously described for the blank 100. chain son 30 li, 301 _2/301 ₃ and 301 ₄ are derived locally in order to relax the latter and allow the passage of the base 320.

Once the base 320 positioned, the son chain 301i, 301 _2/301 ₃ and 301 ₄ are tightened in order to be laminated respectively on the first retaining tab 321 (li wire 30), the body 323 ₍₂ and son 301 301 ₃ ) and on the second retaining tab 325 (wire 301 ₄ ).

After forming and densiflcation of the blank 300 as shown in Figure 14, a piece of composite material 350 is obtained comprising a fastener corresponding to the base 320 whose body 323 and the retaining lugs 321 and 325 are retained on the piece 250 both by the warp son 201i and 201 ₂ and by the polymerized resin 203 (matrix) and at the end of which are present fixing portions 222, 223, 232 and 233 having a flattened shape to provide a sufficient surface for the attachment of other elements such as jumpers or mounting brackets of equipment.

In the case of the use of a fastener element initially having a rod shape as described above with reference to FIGS. 10 to 12, a fastening element of the same type as the base 320 described above may be obtained by inserting under a plurality of threads of the blank a rod of suitable length and by crushing parts of the rod situated at an intermediate distance from the two ends thereof in order to form fixing portions which are extended by legs of detention.

Furthermore, the mechanical strength of the fasteners can be further increased by covering the face of the fastening portions of the fasteners located on the side of the fiber blank with an adhesive compatible with the matrix used for densiflcation. The parts of the fastening elements other than the fixing portions may be placed indifferently under warp threads, weft threads, or both under warp and weft threads (arrangement of the elements at 45 ° to the threads). warp and weft directions).

In the embodiments described above, the integration of a fastener element into the fibrous structure is achieved by passing the body of the element under fibers of the fibrous structure which are stretched locally and then stretched after the passage and positioning the body of the fasteners under these wires.

According to an alternative embodiment, the bodies of the fasteners can be clamped in son of the fibrous structure at the time of weaving thereof. In this case, one or more fasteners, such as for example the bases 120, 130 and 320, or a plurality of pieces intended to form fixing elements, such as the rods 22 and 23, are arranged on the fibrous structure. The fastening elements thus disposed are then woven with one or more additional layers on the surface of the texture, a portion of the wires of this or these additional layers enclosing the fastening elements or the parts intended to form these elements. Depending on the density of the weave of this or these additional layers, the son possibly present above the fastening portions of the fasteners or parts of the parts intended to subsequently form the fixing portions of the fastening elements, such as the parts of the stems. 22, 23 to be crushed to form the attachment portions, are separated from these portions or parts and / or cut locally. The further manufacture of the composite material part comprising fastening elements continues as already described above.

Claims

A fibrous structure (100) for reinforcing a workpiece (10) made of a composite material, said structure being obtained by multilayer weaving between a plurality of layers of warp threads (101) and a plurality of weft thread layers (102),

characterized in that the fibrous structure (100) further comprises at least one of its faces one or more fastening elements (12, 13), each fastening element comprising a body (121, 131) disposed at least partially under yarns (10li, 10) present on one side of said fibrous structure and at least one attachment portion (122; 132) located above said yarns.

2. Structure according to claim 1, characterized in that each fastening element (12; 13) comprises a first and a second fixing portions (122, 123; 132, 133) extending on each side of said body (121; 131) and above the threads of the fibrous structure (100).

3. Structure according to claim 2, characterized in that said first and second portions (122, 123; 132, 133) have a flattened shape.

4. Structure according to any one of claims 1 to 3, characterized in that each fixing portion (322; 324) is extended by a retaining tab (321; 325) disposed under one or more son of the fibrous structure.

5. Composite material part comprising a fibrous structure according to any one of claims 1 to 5 densified by a matrix.

6. Part according to claim 5, characterized in that each fastening element (12; 13) further comprises a jumper (125; 135) fixed on each fixing portion.

7. Part according to claim 5 or 6, characterized in that it constitutes a casing (10) of aeronautical engine.

8. A turboprop comprising an aircraft engine casing according to claim 7.

9. Aircraft equipped with at least one turboprop engine according to claim 8.

10. A method of producing a composite material part comprising the following steps;

- producing a fibrous structure (100) by multilayer weaving between a plurality of warp son layers (101) and a plurality of weft son layers (102),

- Shaping the fibrous structure (100),

densification of the fibrous preform (160) with a matrix (103),

characterized in that it further comprises, prior to densification of the preform, insertion under wires (ΙΟΙι, IOI2) present on one face of the fibrous structure of a body (121; 131) of one or more fastening elements (12; 13), each fastening element further comprising at least one fastening portion (122; 132) located above said wires.

11. Method according to claim 10, characterized in that, during the insertion under wires (10i, 10I2) accessible from one side of the fibrous structure (100) of the body (121; 131) of each fastening element ( 12, 13), said wires are expanded so as to allow the passage of each fastener, said threads being then retensioned.

12. The method of claim 10, characterized in that each fastener is disposed on the fibrous structure being woven, one or more additional layers being woven over each fastener.

13. A method according to any one of claims 10 to 12, characterized in that, during the insertion of each fastener under son (10li, 10I2) of the fibrous structure (100), the fastening element has a rod shape (22; 23) and that after said insertion, at least a portion of the fastener element located above the threads of the fibrous structure is crushed to form a fastening portion (222; 223; 232; 234).

14. A method according to any one of claims 10 to 13, characterized in that each fixing portion (322; 324) is extended by a retaining tab (321; 325) which is arranged under one or more son of the structure fibrous during the insertion of the fastening element (s) under threads of the fibrous structure.

15. A method according to any one of claims 10 to 14, characterized in that each fixing element (12, 13) further comprises a jumper (125; 135) fixed on each fixing portion (122; 123; 132; 133).